1. Field of the Invention
The present invention relates to a dielectric film layered product, a production method of the dielectric film layered product, a semiconductor apparatus and a production method of the semiconductor apparatus. In particular, the present invention relates to a dielectric film layered product and a production method of the dielectric film layered product for achieving a low leak current and a good boron leakage tolerance.
Priority is claimed on Japanese Patent Applications No. 2007-005923, filed Jan. 15, 2007, and No. 2007-294306, filed Nov. 13, 2007, the contents of which are incorporated herein by reference.
2. Description of Related Art
In recent years, semiconductor apparatuses have had larger capacities than before and have been gradually becoming even larger. In this sense, semiconductor devices have been more and more refined. Along with the progress in refining the semiconductor devices, the pattern size has been becoming smaller in a plane due to lithography technology, and moreover the thickness of a film has been becoming smaller. For example, there is demand for a gate insulator of a transistor which has a thickness of 3 nm or less. However, there are various problems with regard to film which has a thickness of 3 nm or less by using a silicon oxidation film used in conventional techniques as a gate insulator.
For example, if the gate insulator is thin, there is a problem in which a gate leak current increases because of direct tunneling phenomena. Moreover, there is a possibility in which a dopant impurity (for example, boron) included in a gate terminal is diffused inside the gate insulator by heat and enters into a silicon substrate under the gate insulator. Such phenomena is called a boron leakage. Therefore, there is a strong need for the gate insulator to have a less leak current and an excellent boron leakage tolerance.
Materials of gate insulator other than silicon oxide are generally well-known such as HfSiON, HfAlON, HfZrSiON and HfZrAlON which are made by using Hf oxide as mother material.
These materials are made in a MOCVD method and the like, and these materials are preferably in a non-crystal state. The reason why these materials are preferably in a non-crystal state is that a grain boundary is necessarily included if a polycrystal is made from a film of such materials. Such a gain boundary causes an increased leak current.
A conventional technique as shown in the following Patent Document 1 is generally known for forming a silicon oxide film including Hf as a non-crystal/amorphous film. In Patent Document 1 shown below, a generation method of a gate insulator is disclosed in which the grain boundary is not generated even after a heating operation at 1000° C. or lower. In accordance with Patent Document 1, in order to obtain a gate insulator, a metal silicate film which is obtained at a metallic ratio of 62% or less and a nitrogen ratio of 30% or higher is formed on a substrate boundary layer made from SiO2, and moreover, on the metal silicate film, another film of silicic acid metal including 50-80% of nitrogen is formed. In other words, it is possible to produce the gate insulator without forming a grain boundary by forming a concentration distribution of nitrogen.
In accordance with the dielectric film of Patent Document 1, nitrogen is included in the film. Therefore, it is considered that the dielectric film has a good boron tolerance. However, in a case in which a certain EOT (Equivalent Oxide Thickness) is required or given, compared to a crystalline film, a non-crystalline film has a lower permittivity, and a smaller physical film thickness. Therefore, there is a problem in a conventional technique described in Patent Document 1, that is, it is difficult to control a gate leak current caused by direct tunneling phenomena.
[Patent Document 1] Japanese Patent Application, First Publication No. 2005-64032